Conducting polymers have been the subject of intense research activity for the past decade. Currently, much work is devoted to the synthesis of conducting polymers for use in a variety of applications. Polyacetylene, the prototype conducting polymer, has been successfully demonstrated to be useful in constructing p-n heterojunctions, Schottky barrier diodes, liquid junction photoelectrochemical solar cells, and, more recently, as the active electrode in polymeric batteries.
The improved electrochemical synthesis of polypyrrole has led to its use as coating for the protection of n-type semiconductors against photocorrosion in photoelectrochemical cells. Research studies have shown that pyrrole and thiophene, five-membered heterocyclic aromatic ring compounds, undergo simultaneous oxidation and polymerization. Conducting polyheterocycles, such as polypyrrole and polythiophene, have demonstrated dramatic improvement in oxidative stability over other conducting polymers. However, polyheterocycles, like other known conducting polymers, are hampered by a limited range of mechanical properties.
Polypyrrole and polythiophene can be synthesized by electrochemical techniques on the surface of an electrode. Electrochemically synthesized polythiophene films are extremely brittle, making it difficult to remove the films from electrode surfaces without fragmentation. Electrochemically synthesized films of polypyrrole are less brittle than polythiophene films. Heretofore, electrochemically synthesized polypyrrole has exhibited poor processibility, i.e., has been difficult to process.